Canadian Infrastructure AlternativesThe theory for how to put a web interface on a legacy application is simple. Introduce middleware that translates between web pages and legacy transactions, and provides a web translation of printed reports. Except for a possible increase in volume, the legacy application continues to see the same things. But the user now works with a web browser. Middleware is described by a simple picture:  There are two approaches to providing the required middleware. One approach has a simple server connected to the legacy application, with most of the work being done by Java applets or ActiveX controls that are shipped to the browser. The other approach does a full translation in the server connected to the legacy application. Interestingly, Canada has middleware companies that follow both approaches. Simware offers Salvo, which provides a powerful server-based object-oriented Web application development environment. The server connected to the legacy application is where all the real work gets done. Farabi Technology has taken the other approach. Their HostFront product provides powerful ActiveX Controls, Java applets, and printer applets which allow the user's browser to interact with a simple server connected to the legacy application. The work takes place in the browser. There are many other middleware solutions available to provide web access to legacy applications. These two Canadian solutions have received positive reviews and are illustrative of the two approaches taken by such middleware suppliers. The business logic required with the new web interface will significantly determine which approach should be used with a particular application. Salvo makes it relatively easy to add complex business logic, either directly or by linking to any of the powerful server-side web development tools. The cost is a significant increase in infrastructure complexity. HostFront eliminates the need for that increased complexity, but does not provide the same level of support for complex business logic. |